Determination of 34 Ozone Depleting Substances in Ambient Air by Gas Chromatography-Mass Spectrometry with Summa Canister Sampling and Pre-Concentration

A method was proposed for determination of 34 ozone depleting substances (ODS) in ambient air by gas chromatography-mass spectrometry (GC-MS) with summa canister sampling and pre-concentration. The ambient air was collected by summa canister alkylated, with pre-concentration, enrichment, and thermal desorption by three-stage cold trap. The desorbed sample was separated on Gas-Pro capillary column (60 m×0.32 mm) under programmed temperature by GC. Full scan (SCAN) mode and selected ion monitoring (SIM) mode were adopted in MS analysis, and external standard method was used for quantification. As shown by the results, linear relationships between values of response and mole fraction of 34 ODS were found in definite ranges, with detection limits (3.14s) in the range of 4.17-11.4 pmol·mol^-1. Test for recovery was made by standard addition method, giving results in the range of 81.4%-95.8%, with RSDs (n=6) of determined values less than 10%. The ambient air samples from a sampling point in Tianjin were analyzed by the above method, and 13 ODS were detected, with the detection amounts of 16.4-456 pmol·mol^-1.